1. Field of the Invention
The present invention relates generally to image reconstruction, and in particular, to a method, apparatus, and article of manufacture for eliminating distortion and skew due to the shaking and vibration in hand-held imaging devices such as optical coherence tomography (OCT)-based endoscopes.
2. Description of the Related Art
(Note: This application references a number of different publications as indicated throughout the specification by reference numbers enclosed in brackets, e.g., [x]. A list of these different publications ordered according to these reference numbers can be found below in the section entitled “References.” Each of these publications is incorporated by reference herein.)
Optical Coherence Tomography (OCT) has been an emerging technology in the field of biomedical imaging since its invention in the 1990s. Its non-invasive nature and high resolution imaging capability makes itself one of the most desirable way imaging biological tissues [1]. Despite its many intriguing advantages, light scattering and/or absorption of tissue are jeopardizing the use of OCT in deep-tissue imaging. For instance, OCT permits only millimeter scale penetration depth for near infrared light [2]. As a potential solution, OCT-based endoscopes, such as an endoscopic needle probe, are capable of penetrating deep into tissues and collecting reflected optical signals from the required depth, which will be further used to reconstruct the structure of the tissue [3-9].
Many OCT-based needle endoscopes have been developed, regardless of their region of inspection, side-imaging [3-6] or forward-imaging [7-10]. In OCT, an A-scan is a one-dimensional scan along the depth axis. A B-scan along another direction, together with A-scan, will generate a cross-section image where signal strength is translated to brightness. Although a few three dimension implementations of OCT have been reported [6], most of these methods deploy different schemes to achieve the secondary dimension scan (B-Scan), which will be combined with the intrinsic OCT depth scan (A-Scan) to form two-dimension images.
The most common application of endoscopic systems is to provide guidance and real-time monitoring during surgeries [11-12], for which a hand-held acquisition system is very much desired and often times inevitable. FIG. 1 illustrates a vitrectomy in ophthalmic surgery [13]. A vitrectomy is a surgical procedure to remove the vitreous humor (i.e., the clear gel that fills the space between the lens and retina of the eyeball) where surgeons insert an endoscopic needle 102 through a standard cannula 104 or scleral incisions (incisions into the sclera [also known as the white of the eye]) on the patient's eye to examine the remnant vitreous [14]. As illustrated, the endoscopic needle may illuminate 106 the organ or object under inspection, collect, and transmit back the reflected signal for image reconstruction.
Since image reconstruction always depends on the relative position between the object and the image acquirer (e.g., the needle 102, in the vitrectomy application), the time-varying position of the image acquirer, like shaking or vibration, imposes a significant impact on the acquired image. While different schemes have different gain, almost all of them have the intrinsic difficulty in this scenario to resolve the real image from the distortion and skew by the shaking and vibration of the image acquirer, which are usually from the operator's hand.